1. Field of the Invention
The present invention relates to a circuit interrupter used in a large power circuit. More particularly, it relates to a circuit interrupter in which an arc-extinction is performed by sucking the arc by a negative pressure caused by a detaching operation of a contact.
2. Description of the Prior Arts
In a conventional circuit interrupter for arc-extinction by utilizing SF.sub.6 gas etc., the gas pressurized by a compressing device is puffed to the arc formed at the current cut-off or the gas pressurized by a cylinder-piston interlocked to a movable contact is puffed to the arc at the current cut-off.
The former has a disadvantage of the requirement of the compressing device which makes a complicated structure and the latter which pressurizes the gas by the cylinder-piston has a disadvantage that a clogging phenomenon is caused at the cut-off of a large current to highly increase the pressure in the cylinder so as to require a large driving force for shifting the movable contact.
Beside the both types of the circuit interrupters, it has been considered to use a circuit interrupter which performs the arc-extinction by the arcing at the current cut-off without using neither the high pressure compressing device nor the system for pressurizing the gas by the driving force.
In accordance with this system, arc energy is too small at the cut-off with a small current, whereby pressurizing in a storage chamber for a gas expanding by the arc is not expected and arc extinction ability is lowered.